(11)	Convertible Preferred Stock Warrant Liability

The Company has historically issued warrants to purchase shares of the Company’s preferred stock in connection with certain preferred stock offerings and note financings.

As of

December

31,

2015,

the outstanding Series D and Series F convertible preferred stock warrants are as follows (in thousands, except per share and share data):

	Exercise		Value				Shares		Estimated Fair Value
	price		at grant		Issue	Expiration	December 31,		December 31,
Share class	per share		date		date	date	2015		2015
Series D	$	0.37	$	0.30	January 2006	January 2016		325,861	$	2
Series D	$	0.37	$	0.30	July 2007	July 2017		203,691		20
Series D	$	0.37	$	0.30	August 2007	August 2017		203,691		20
Series D	$	0.37	$	0.30	September 2007	September 2017		203,691		20
Series F	$	0.64	$	0.27	April 2013	April 2016		888,176		94
Series F	$	0.64	$	0.28	April 2013	October 2017		482,699		115
Series F	$	0.64	$	0.28	April 2013	November 2017		11,620		3
Series F	$	0.64	$	0.27	May 2013	May 2016		13,169		1
								2,332,598	$	275

Upon the completion of the Merger, the Company exchanged

20%

and

10%

of outstanding Series D and Series F convertible preferred stock warrants for

81,460

and

48,223

shares of the Company’s common stock, respectively, and cancelled the remaining convertible preferred stock warrants pursuant to the Merger Agreement. Upon the completion of the Merger, the valuation of the convertible preferred stock warrant liability was determined based on the settlement value of the common stock exchanged for the warrants, amounting to

$25,000,

and the Company reclassified the balance of the convertible preferred stock warrant liability to additional paid-in capital.

The fair value of the warrants at

December

31,

2015

included in current liabilities in the consolidated balance sheet and was determined using the BSM valuation model using the following assumptions:

	December 31, 2015
Risk-free interest rate	0.14	–	0.86%
Volatility	98.5	–	116.25%
Dividend yield	None
Contractual term (in years)	0.1	–	1.8

The contractual term of the warrants represents the period of time remaining before the warrant expires. Since prior to the Merger, the Company’s shares were not publicly traded and its shares were rarely traded privately, expected volatility was estimated based on the average historical volatility of similar entities with publicly traded shares. The risk free rate was based on the U.S. Treasury yield curve with a maturity equal to the remaining contractual term of the warrant.